An existing TFT-LCD CF (color filter) process is shown in FIG. 1 and FIG. 2. Wherein FIG. 1 is a structural schematic diagram of a color film substrate in the prior art; FIG. 2 is a structural schematic diagram of a mask plate in the prior art. The mask plate in the prior art generally comprises: a first region 07 one-to-one corresponding to each subpixel unit, and a second region 08 between two adjacent first regions 07. The photoresist used for the color filter layer is generally negative photoresist; therefore the first region 07 of the mask plate is fully transparent, the second region 08 is fully opaque; the formed pattern of the color filter layer is shown in FIG. 1. A color film substrate in the prior art mainly comprises: a glass substrate 01, a black matrix layer 02, a color filter layer 03, a planarization layer 04, a spacer 05, and a transparent electrode layer 06. In order to prevent the occurrence of light leakage, the color filter layer 03 should overlap with a part of the black matrix layer 02; in order to avoid an influence on the image quality due to the segment difference of the overlapping part, the planarization layer 04 is required; this will add a process, increasing the cost of production; moreover, the planarization layer 04 will reduce the transmittance of the color film substrate, resulting in the decrease of contrast.